This at once forces a consideration as to how a battleship differs from an armoured cruiser. Fundamentally the battleship sacrifices speed for a superior armament and protective armour. It is this superiority of speed that enables an enemy’s ships to be overhauled or evaded that constitutes the real difference between the two. At the present moment naval experience is not sufficiently ripe to abolish totally the building of battleships so long as other countries do not do so.
But it is evidently an absolute necessity in future construction to make the speed of the battleship approach as nearly as possible that of the armoured cruiser.
Next consider the case of the armoured cruiser.
In the old days the frigate was the cruiser, she was unarmoured, that is, her sides were so much thinner than those of the battleship that she was not able to fight in the line of battle, but the weak gun fire of those days permitted close scouting by such unprotected vessels, she could approach a battleship squadron very closely without fear of damage, she could sail round a fleet and count their numbers without danger to herself, unless chased off by other frigates, she was a scout and a commerce destroyer. Similarly with present day armoured cruisers, they can force their way up to within sight of a fleet, and observe them, unless chased off by other armoured cruisers, but to do this they have to be given a certain amount of protective armour.
The range of eyesight has remained constant, that of gunfire has increased. Speed is a necessity to ensure safety, armour protection to ensure vision.
It is evident, from the above considerations, that the functions of the frigate have devolved on the armoured cruiser to a greater extent than have the functions of the line of battleship devolved on the modern battleship.
But how about the unarmoured cruisers and those of low speed?
With loss of protection a cruiser loses her power of reasonable approach for observation purposes, and if to this be added a loss of reasonable speed her safety is gone. Cruisers without high speed and protection are entirely and absolutely useless.
Every vessel that has not high scouting speed, or the highest defensive and offensive powers, is useless for fighting purposes.
This is true of every class of vessel between the first class armoured cruiser and the fast torpedo vessel.